February 14, 2012 at 7:42 am #233976
I did a search on this and found some information but not very many specifics. So I thought I broadcast my question.
I started looking at what it would take to repaint the body and found myself scratching my head with questions.
I know I can’t use simple bondo and that I need a fiberglass repair kit with fiberglass strands in the mix…which I have. We filled a few pock marks, sanded and then primed with a basic automotive primer.
To my surprise, the primer never stuck. It looked like I was painting on a highly waxed surface. The paint almost beaded. I took a rag and was able to wipe almost all of it off.
So, what do I need to know about painting a 30 year old fiberglass, gelcoat body?
How do I prep for primer? What primer should I use?
Thanks for your feedback.February 14, 2012 at 8:09 am #249139Scott A ChynowethParticipant
Sorry I’m not an expert.However you are going to have to break the glaze of the gelcoat for anything to stick.I have not reaserch but I would think the gelcoat is very similar to the clearcoat on cars today,just thicker.
Give it try with some 400 and see if paint sticks.Rattle can is not the best solution,generally a good primer needs a 400 grit tooth.Also be sure to wipe down with some prep solve or other good prepaint cleaning product.February 14, 2012 at 8:30 am #249140RoyalParticipant
I too am no expert on fiberglass. But, I have owned a number of boats. That is where I would go, – ask a reputable boat guy. Awlgrip is a popular boat paint that I have used.February 14, 2012 at 9:24 am #249141Mark KonradParticipant
Rockyx Hope this helps. Found it on line.
Surface prep is very important. Paint will not stick to oily or greasy surfaces. The oil from your hands is enough to prevent adhesion. So a clean surface is vital. Also, if the surface is too rough or has gouges in it those blemishes will show right through the paint.
Paint will not adhere well to glossy surfaces so sanding is also a vital step. This is especially true of you are painting over a previous coating of poly or epoxy. The best bet it to use a very fine “wet” sandpaper to be sure you have just enough roughness for the paint to stick.
Contrary to popular rumor you can paint a single part paint over a two part paint. It is not advisable to attempt to paint with a “two parter” over a single part paint though I’ve had good luck with this too. The key, of course, is preparation.
Rules of Thumb: If you are painting over;
- a fresh fiberglass or metal surface use a primer first
- a pre-primed surface, rough sanding (120 grit) first
- a first coat painted surface fine sandpaper (400 grit) first
- Succeeding layers wet sanding (1000 and higher grit)
The steps for painting with primer are not as rigid as the finish coats. By and large you can apply primer a bit thicker and you certainly don’t need a “tip” method to smooth it out. Primer provides an excellent bond between fiberglass and the finish paint. It also provides an additional moisture barrier.
Be sure that each surface to be painted is clean and completely dry.
The typical steps to preparing the surface just prior to painting is to sand, blow or brush the surface free of particles, denatured alcohol rub, water wipe-down, and a tack rag.February 14, 2012 at 9:58 am #249142newkitmanParticipant
Here is a link to the assembly manual in the Download Manuals section at the left. Page 77 – 79 of the manual covers how to repair and paint the Jelcoat surface. I would imagine that the procedure is the same for a full paint after repair. Its the process I’m going to use on a crack by the engine cover on the body of my TD just as soon as the weather warms up. Hopefully you’ll glean something from those pages.
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackFebruary 14, 2012 at 10:09 am #249143Paul MossbergKeymaster
Gelcoat is a thick color coat that is sprayed into the mold before the fiberglass is laid or shot into the mold.
It is typically composed of expoxy or polyester resins, more similar to fiberglass resins than to today’s clear coat. Even thirty year old gelcoat will have residual oils in it, and gelcoat is relatively porous so it may even have absorbed “stuff” over the years.
You can paint over the gelcoat, but will have to wet sand the entire body first.
Always remember the boating industry has far more experience with this than car guys. I always search boating forums for info.
This is one of the most informative artiucles I have run across on painting over gelcoat:
Another painting over gelcoat discussion:
Here is a good discussion on refinishing gelcoat:
If you only have chalking and no cracking, you should be able to restore the shine. Gelcoat is much thicker than traditional paint and can take a lot of wet sanding and buffing. Here’s a good “how to” on restoring the shine (although I hope you don’t have to worry about fish blood!):
Gelcoat can also be repaired:
Hope this stuff helps!
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster
If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)February 14, 2012 at 10:53 am #249144
Great feedback everyone! I knew I could count on you.
One step I absent mindedly missed was chemically cleaning the surface after the sanding. Makes me feel kinda silly since I did all this meticulously when painting my headlights.
I was working on one item while my son was working on the car and I just jumped up and wiped it with a towel and then sprayed primer on it.
I’ll go back tonight and follow the proper steps and see if I get a different result.
Thanks again for all the good info.February 15, 2012 at 9:59 am #249145
Ok. I feel pretty red faced on this one.I went back and followed my own steps for prep and paint (as pointed out by several in this thread).I sanded, washed, wiped down with mineral spirits, ran a tack clothe, then primed. Worked perfect!I guess I got a little excited about finally working on the body.February 15, 2012 at 11:13 am #249146ray10Participant
Rocky , this site is more for a refreasher course on gel coat repair ,but it will give you a good idea on how to do it.
http://www.arcgis.com/home/webmap/viewer.html?webmap=7f9174ad614e43b680deba085b0abf48February 16, 2012 at 7:43 pm #249147Steve CritesParticipant
You could respray gelcoat and have a fresh base to work on. Gelcoat can be applied with normal spray gun with 1.8 mm tip. Check out the forum of Kevin Tetz, (the guy on Spike TV “Trucks”) at paintucation.com. Lots of info there for us hobby painters/refinishers.
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